A fuel cell is a device that generates electricity by a chemical reaction. Among various fuel cells, solid oxide fuel cells use a hard, ceramic compound of metal (e.g., calcium or zirconium) oxide as an electrolyte. Typically, in the solid oxide fuel cells, an oxygen gas, such as O2, is reduced to oxygen ions (O2−) at the cathode, and a fuel gas, such as hydrogen gas (H2) gas, is oxidized with the oxygen ions to form water at the anode.
Interconnects are one of the critical issues limiting commercialization of solid oxide fuel cells. Currently, most companies and researchers working with planar cells are using coated metal interconnects. While metal interconnects are relatively easy to fabricate and process, they generally suffer from high power degradation rates (e.g. 10%/1,000 h) partly due to formation of metal oxides, such as Cr2O3, at an interconnect-anode/cathode interface during operation. Ceramic interconnects based on lanthanum chromites (LaCrO3) have lower degradation rates than metal interconnects partly due to relatively high thermodynamic stability and low Cr vapor pressure of LaCrO3 compared to Cr2O3 formed on interfaces of the metal interconnects and electrode. However, lanthanum chromites generally are difficult to fully densify and require high temperatures, such as at or above about 1,600° C., for sintering. Although certain doped lanthanum chromites, such as strontium-doped and calcium-doped lanthanum chromites, can be sintered at lower temperatures, they tend to be either unstable or reactive with an electrolyte (e.g., a zirconia electrolyte) and/or an anode.
Therefore, there is a need for development of new interconnects for solid oxide fuel cells, addressing one or more of the aforementioned problems.